Demonstration of freedom from Chlamydia pecorum in koalas from Kangaroo Island, South Australia

To demonstrate freedom from Chlamydia pecorum in Kangaroo Island koalas, historical clinical records (n=13081) were provided by the South Australian Government's Department for Environment and Water (DEW) koala sterilisation program and surveyed koalas from November 2014 to February 2017 (n=170) in conjunction with the DEW program. A scenario tree modelling approach was used with probability of freedom of a given year n (P(free)_i) estimated using the bayesian calculation from the prior probability of freedom (P(free)_i-1) and the surveillance system sensitivity (SSe_i) and specificity (SSp_i) reflecting the strength of the evidence of absence collected during the year.